On Tue, Nov 24, 2015 at 01:36:17PM +0100, Vlastimil Babka wrote: > During migration, page_owner info is now copied with the rest of the page, so > the stacktrace leading to free page allocation during migration is > overwritten. > For debugging purposes, it might be however useful to know that the page has > been migrated since its initial allocation. This might happen many times > during > the lifetime for different reasons and fully tracking this, especially with > stacktraces would incur extra memory costs. As a compromise, store and print > the migrate_reason of the last migration that occured to the page. This is > enough to distinguish compaction, numa balancing etc. > > Example page_owner entry after the patch: > > Page allocated via order 0, mask 0x24280ca > PFN 669757 type Reclaimable Block 1308 type Reclaimable Flags UDLA > [<ffffffff81164e8a>] __alloc_pages_nodemask+0x15a/0xa30 > [<ffffffff811ad435>] alloc_pages_vma+0xb5/0x250 > [<ffffffff8118ba54>] handle_mm_fault+0x1304/0x1820 > [<ffffffff81051213>] __do_page_fault+0x183/0x3f0 > [<ffffffff810514a2>] do_page_fault+0x22/0x30 > [<ffffffff81573ba8>] page_fault+0x28/0x30 > [<ffffffffffffffff>] 0xffffffffffffffff > Page has been migrated, last migrate reason: compaction > > Signed-off-by: Vlastimil Babka <[email protected]> > --- > include/linux/migrate.h | 6 +++++- > include/linux/page_ext.h | 1 + > include/linux/page_owner.h | 9 +++++++++ > mm/migrate.c | 20 +++++++++++++++++--- > mm/page_owner.c | 17 +++++++++++++++++ > 5 files changed, 49 insertions(+), 4 deletions(-) > > diff --git a/include/linux/migrate.h b/include/linux/migrate.h > index cac1c09..ab92a8c 100644 > --- a/include/linux/migrate.h > +++ b/include/linux/migrate.h > @@ -23,9 +23,13 @@ enum migrate_reason { > MR_SYSCALL, /* also applies to cpusets */ > MR_MEMPOLICY_MBIND, > MR_NUMA_MISPLACED, > - MR_CMA > + MR_CMA, > + MR_TYPES > }; > > +/* In mm/migrate.c; also keep sync with include/trace/events/migrate.h */ > +extern char * migrate_reason_names[MR_TYPES]; > + > #ifdef CONFIG_MIGRATION > > extern void putback_movable_pages(struct list_head *l); > diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h > index 17f118a..e1fe7cf 100644 > --- a/include/linux/page_ext.h > +++ b/include/linux/page_ext.h > @@ -45,6 +45,7 @@ struct page_ext { > unsigned int order; > gfp_t gfp_mask; > unsigned int nr_entries; > + int last_migrate_reason; > unsigned long trace_entries[8]; > #endif > }; > diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h > index 6440daa..555893b 100644 > --- a/include/linux/page_owner.h > +++ b/include/linux/page_owner.h > @@ -12,6 +12,7 @@ extern void __set_page_owner(struct page *page, > unsigned int order, gfp_t gfp_mask); > extern gfp_t __get_page_owner_gfp(struct page *page); > extern void __copy_page_owner(struct page *oldpage, struct page *newpage); > +extern void __set_page_owner_migrate_reason(struct page *page, int reason); > > static inline void reset_page_owner(struct page *page, unsigned int order) > { > @@ -38,6 +39,11 @@ static inline void copy_page_owner(struct page *oldpage, > struct page *newpage) > if (static_branch_unlikely(&page_owner_inited)) > __copy_page_owner(oldpage, newpage); > } > +static inline void set_page_owner_migrate_reason(struct page *page, int > reason) > +{ > + if (static_branch_unlikely(&page_owner_inited)) > + __set_page_owner_migrate_reason(page, reason); > +} > #else > static inline void reset_page_owner(struct page *page, unsigned int order) > { > @@ -53,5 +59,8 @@ static inline gfp_t get_page_owner_gfp(struct page *page) > static inline void copy_page_owner(struct page *oldpage, struct page > *newpage) > { > } > +static inline void set_page_owner_migrate_reason(struct page *page, int > reason) > +{ > +} > #endif /* CONFIG_PAGE_OWNER */ > #endif /* __LINUX_PAGE_OWNER_H */ > diff --git a/mm/migrate.c b/mm/migrate.c > index 863a0f1..12e9ab9 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -47,6 +47,16 @@ > > #include "internal.h" > > +char *migrate_reason_names[MR_TYPES] = { > + "compaction", > + "memory_failure", > + "memory_hotplug", > + "syscall_or_cpuset", > + "mempolicy_mbind", > + "numa_misplaced", > + "cma", > +}; > + > /* > * migrate_prep() needs to be called before we start compiling a list of > pages > * to be migrated using isolate_lru_page(). If scheduling work on other CPUs > is > @@ -955,8 +965,10 @@ static ICE_noinline int unmap_and_move(new_page_t > get_new_page, > } > > rc = __unmap_and_move(page, newpage, force, mode); > - if (rc == MIGRATEPAGE_SUCCESS) > + if (rc == MIGRATEPAGE_SUCCESS) { > put_new_page = NULL; > + set_page_owner_migrate_reason(newpage, reason); > + } > > out: > if (rc != -EAGAIN) { > @@ -1021,7 +1033,7 @@ static ICE_noinline int unmap_and_move(new_page_t > get_new_page, > static int unmap_and_move_huge_page(new_page_t get_new_page, > free_page_t put_new_page, unsigned long private, > struct page *hpage, int force, > - enum migrate_mode mode) > + enum migrate_mode mode, int reason) > { > int rc = -EAGAIN; > int *result = NULL; > @@ -1079,6 +1091,7 @@ static int unmap_and_move_huge_page(new_page_t > get_new_page, > if (rc == MIGRATEPAGE_SUCCESS) { > hugetlb_cgroup_migrate(hpage, new_hpage); > put_new_page = NULL; > + set_page_owner_migrate_reason(new_hpage, reason); > } > > unlock_page(hpage); > @@ -1151,7 +1164,7 @@ int migrate_pages(struct list_head *from, new_page_t > get_new_page, > if (PageHuge(page)) > rc = unmap_and_move_huge_page(get_new_page, > put_new_page, private, page, > - pass > 2, mode); > + pass > 2, mode, reason); > else > rc = unmap_and_move(get_new_page, put_new_page, > private, page, pass > 2, mode, > @@ -1842,6 +1855,7 @@ int migrate_misplaced_transhuge_page(struct mm_struct > *mm, > set_page_memcg(new_page, page_memcg(page)); > set_page_memcg(page, NULL); > page_remove_rmap(page, true); > + set_page_owner_migrate_reason(new_page, MR_NUMA_MISPLACED); > > spin_unlock(ptl); > mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); > diff --git a/mm/page_owner.c b/mm/page_owner.c > index f571e55..59fd6f1 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -6,6 +6,7 @@ > #include <linux/stacktrace.h> > #include <linux/page_owner.h> > #include <linux/jump_label.h> > +#include <linux/migrate.h> > #include "internal.h" > > static bool page_owner_disabled = true; > @@ -73,10 +74,18 @@ void __set_page_owner(struct page *page, unsigned int > order, gfp_t gfp_mask) > page_ext->order = order; > page_ext->gfp_mask = gfp_mask; > page_ext->nr_entries = trace.nr_entries; > + page_ext->last_migrate_reason = -1; > > __set_bit(PAGE_EXT_OWNER, &page_ext->flags); > } > > +void __set_page_owner_migrate_reason(struct page *page, int reason) > +{ > + struct page_ext *page_ext = lookup_page_ext(page); > + > + page_ext->last_migrate_reason = reason; > +} > + > gfp_t __get_page_owner_gfp(struct page *page) > { > struct page_ext *page_ext = lookup_page_ext(page); > @@ -161,6 +170,14 @@ print_page_owner(char __user *buf, size_t count, > unsigned long pfn, > if (ret >= count) > goto err; > > + if (page_ext->last_migrate_reason != -1) { > + ret += snprintf(kbuf + ret, count - ret, > + "Page has been migrated, last migrate reason: %s\n", > + migrate_reason_names[page_ext->last_migrate_reason]); > + if (ret >= count) > + goto err; > + } > +
migrate_reason_names is defined if CONFIG_MIGRATION is enabled so it would cause build failure in case of !CONFIG_MIGRATION and CONFIG_PAGE_OWNER. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
